The user of a pneumatic tool requiring a steady source of compressed air for operation is usually limited in mobility by a length of air hose connected to an air compressor that is stationary, or at least limited in mobility. A conventional air compressor is often limited in mobility due to a large tank for storing compressed air, a non-electric motor driving the compressor that may emit harmful gases and requires a fuel source that adds weight and dimension, or an electric motor requiring connection to a fixed power source such as an AC outlet.
U.S. Pat. Nos. 6,692,239 and 6,589,024 of Nishikawa et al. and U.S. Pat. No. 5,030,065 of Baumann teach radially disposed reciprocating compression mechanisms, opposed pairs of which are each linked by a respective yoke mechanism to drive reciprocation thereof.
Japanese Patent Abstract Publication No. 59190486 teaches a reciprocating air compressor having its cylinders secured radially on the polygonal peripheral wall of a crankcase to reduce the front-to-rear length of the compressor. Conventional connecting rod assemblies used in such radial cylinder arrangements typically use pins to pivotally connect a master connecting rod to other connecting rods. Such pins may prematurely fail when significantly reduced in scale for use in a compact portable device and may involve a significant number of assembly steps to complete connection between the master connecting rod and all of the pistons.
Battery-powered portable air compressors having either small tanks or no tanks at all have been developed in an attempt to avoid the mobility limitations of conventional compressors listed above. However, such battery-powered types of compressors typically do not provide enough airflow to be useful for powering pneumatic tools, which require relatively high amounts of air pressure provided on a relatively continuous basis for optimal operation. These compressors are typically reciprocating compressors that feature only a single piston/cylinder arrangement in the interest of keeping the compressors relatively small for the purpose of improving portability.
International Publication Number WO 01/29421 teaches a battery powered portable compressor system featuring a two-cylinder compressor, of the type described in U.S. Pat. No. 4,715,787 mounted on a belt and storing compressed air within a hose connecting the compressor to a pneumatic tool.
U.S. Pat. No. 3,931,554 of Spentzas teaches a two-piston reciprocating motor compressor that, in the embodiment of FIG. 9, is battery operated.
U.S. Patent Application Publication Number 2002/0158102 of Patton et al. teaches a portable pneumatic tool having an onboard single-piston compressor assembly that can be powered by a detachable battery and a portable single-piston compressor assembly that can be borne by a user to power a pneumatic tool.
U.S. Pat. No. 6,089,835 of Suzuura et al. teaches a portable single-piston compressor having a motor and a power transmitting mechanism supported in a two-piece housing and an air tank defined by an outer surface of the second housing and an inside surface of a third housing mounted to the second housing.
U.S. Patent Application Publication number 2005/0214136 of Tsai teaches a portable compressor system including a knapsack divided into two chambers, one of which contains a DC motor, an air cylinder, an air storage flask, a pressure switch and a quick connector, and the other containing a battery and a control box.
U.S. Pat. No. 3,961,868 teaches a small compressor having a single cylinder with a wobble type piston having the intake port valve provided on the piston head to introduce air from the crank case into the cylinder.
A worker using both portable electric tools and pneumatic tools powered by a portable compressor at one job site typically must carry two or more separate battery packs, as conventional portable air compressors and conventional portable electric tools are powered by separate dedicated battery packs.
U.S. Pat. No. 5,095,259 teaches a system for operating a plurality of different DC power tools and appliances one-at-a-time. However, the use of such a system to power both an electric tool and a portable compressor for a pneumatic tool involves the running of two separate power delivery lines, an electrical cord from the battery pack for connection to the electric tool or the compressor and an air hose from the compressor to the pneumatic tool.
Conventional compressors and pumps often use reed valves using a thin, flexible strip of metal or fiberglass fixed at one end and bendable to open and close over a port in response to differences in pressure on opposite sides of the valve. These valves may break off or fail to seat properly after repeated exposure to the bending stresses experienced in their operation. Metal reeds also retain heat which may be considered wasted energy and may corrode over time with exposure to moisture.
Conventional pumps used, for example, to withdraw production-inhibiting water from oil and gas wells, may fail relatively quickly when run continuously with exposure to brackish water or other fluids containing abrasive particulate material such as sulfur or sand. More particularly, the reeds in such a pump may wear or corrode at an increased rate as a result of such exposure.